Shell for composition brake shoes



M. R. DE FRANCE SHELL FOR COMPOSITION BRAKE SHOES Filed July as, 1925 2Sheets-Sheet 1 Murre R. De Trance WM awm his af'farnlq Dec. 1 1925 M. R.DE FRANCE SHELL FOR COMPOSITION BRAKE SHOES Filed Jul 23, 1925 2sheetssheet 2 FIG. 3

FIG. 5

FIG. 5

l2 IN VENTOR' M urreII R. De Trance 129 mm, wnm

25 points where protection and binding. are

Patented Dec. 1, 1925.

UNITED STATES MURBELL R. DE FRANCE, OF BELLEVUE, PENNSYLVANIA.

SHELL FOR COMPOSITION BRAKE SHOES.

Application filed July 23, 1925.

i To all whom it may concern:

Be it known that I, MURRELL R. DE FRANCE, a citizen of the UnitedStates, residing at Bellevue, in the county of Allegheny and State ofPennsylvania, have in- *-*1 vented a new and useful Improvement in aShell for Composition Brake Shoes, of which the following is aspecification.

This invention relates to a pressed steel brake shoe shell for use as acontainer for frictional composition toprovide a complete pressed steelshell for use with a composition filler of frictional material. Thesefeatures are as follows: A shell for a composition filler which ispressed from a blank which may be easily formed, a blank which may bepressed to form the containing shell patents, among without tearing themetal at any point, a shell which is strong at the areas subjected togreatest stress, a shell which protects and holds together thecomposition filler at the most needed, a shell which presents arelatively small area of metal to the Wheel to which the brake shoe isapplied during wearing away of the shoe and throughout the entire usefullife thereof.

The desirability of one or more of such features is fully explained invarious prior which are the patent to De France No. 1,114,343, datedOctober 20,1914, the patent to De France No. 1,303,173, dated May 6,1919, the patent to Pettis No. 1,503,514, dated August 5, 1924, and thea plication to De France Serial No. 743,93 filed Oct. 16, 1924.

In the accompanying drawings Figure 1 is a plan view of a blank incondition to be pressed into the brake shoe shell of the presentinvention; Figure 2 is a cross section View thereof on the line 22Figure 1, showing in dotted lines the position assumed by the metalalongthe edges of the blank in forming the sides of the shell; Figure 3is a side elevation of the completed brake shoe with the compositionfiller of frictional material in the shell, Figure 4 is a bottom planview of the shell without the composition filler therein; Figure 5 isa.cross sectional view on the line 5-5 Figure 3; Figure 6 is an endelevation of the brake shoe; Figure 7 is a fragmentary elevation of aportion Serial No. 45,551.

of one side of the brake shoe shell, showing the shell in unused or veryslightly used condition; Figure 8 is a bottom plan View of the shellportion shown in Figure 7, showingthe distribution of the metal whichcomes into contact with the tread of a wheel; Figure 9 is a fragmentaryelevation of a portion of one side of the brake shoe shell, showing theshell partially worn down; and Figure 10 is a bottom plan view of theshell portion shown in Figure9, illustrating the distribution of themetal which comes into contact with the tread of a wheel.

Ill the drawings the reference numeral 1 designates generally the blankfrom which the brake shoe shell of the present invention is pressed.This blank is rolled to provide a central longitudinally extendingportion of relatively great thickness, and side portions 3 taperingoutwardly to the edges of the blank. The central portion 2 of the pblank becomes eventually.the back and ends of the shell; and the sideportions 3 of the blank become the sides of the shell, while pravidingsome metal which goes into the en s.

The blank is then punched into the form in;

shown in Figure 1. By this punching opera tion the central portion 2 ofthe blank is provided with slots 4 for the attachment of a lug to engagethe brake shoe hanger, and with slots 5 for the atttachment of the endlugs of the brake shoe. The side portions 3 of the blank are alsopunched so that they form a plurality of strips or tabs 6,

with intervening apertures 7 which extend 7 completely to the edge ofthe blank.

The apertures 7, punched from the side portions of the blank, are ofgreatest. width adjacent'the central portion of the blank and decreasein width gradually toward the edge of the blank. strips 6 are of leastwidth adjacent the central portion of the blank, and increase in widthgradually toward the edge of the blank.

correspondinglythe v In the pressing operation, the sidesand ends arefolded down so that the central portion 2 of the blank becomes the back9 and ends 10 of the brake shoe shell, while the side portions 3 of theblank become the sides 11 of the brake shoe shell. During this pressingoperation a certain amount of metal from the side portions of the blankflows into the end portions 10 of the shell.

In order to accommodate this surplus metal, 1,;

" reticulated sides, as heretoforedesigned, a

relatively} great loss has been suffered 'due to pulling or tearing thesides of the shell from the back during the pressing operation. lViththis dorm, however, the relatively great amountof metal along the lineof the fold, and at-the base of the side strips 6, prevents su'chtearing and pulling away.

The back 9' of the brake shoe shell, being formed of the thick centralportion) of the blank,is of'relatively great thickness and strength. Itis thusenab'led to resist the forces tending tofpull theshoe apart inuse after the body has-become worn thin.

When the brake shoe shell, designated generally by the reference numeral14,'has

jacent'the lower edges of the sides, thefillilngcomp'ositlon hardening1n the apertures been pressed :to form; the filling block '15 o f-a'suitable frictional composition, inplastic-condition, is pressedthereinto. 'As'the side apertures 7 occupy eacha "relatively great area,no more-pressure is necesaryto force the-composition through them thanneed be exerted in pressing the filling'composition into a shell havingsides of acon- 'tinuous extent ofmateria'l. All varieties of compositionwhich may be used are so composed that after being pressed into thebrake shoe shell they "harden upon baking or'mere exposure to the air.

As thewidth of the apertures is least adcauses them to form an anchoragefor the entire block of filling compositionequal'to that secured by theprovision ofreticu'lated or perforated sides. Since the greatest 'areaembraced by the aperturesis adjacent the back of the shell, their formalso-:contributes to the rapid andperfect drying and hardening of thecomposition. This is the case In actual use ofthe brake shoe, the onlyportions of the sides'll'which are subjected to stress are the areasadjacent the ends and. closeto the back ofthe brake shoe. At such areasthere is a turning moment, due to the engagement of the brake shoewith'the-wheel to which it is applied, which tends in some degree to pull thebrake shoe apart. Asa special precaution in meeting this tendency,

the apertures -16,=which"are adjacent the ends of the shell are made oflesser extent than the other apertures 7 in the sides. This provides agreater-extent of metal at these general areas 17 on the sides of theshell. Durlng'lrandllng of the brake shoe prior to its mounting for use,and even after such mounting, the composition filler of the brake shoeis susceptible to chipping or cracking due to blows received by thelower edges of =the filling block. In I this I connection it should benoted that the widest portions of the sidestripsG ofthe shell liealongthese edges and serve to adequately protect the same duringhandlingand whi'le the depth of tlre brake shoe remains sufficient torender probable the reception of blows along the edges of the shoe.

lt is a well lmownfact that injury to the tread of a wheelto which abrake shoe is applied results from the presentationof-a relatively"great 'area of the hardmetal of the brake shoeshell to the 'tread ofthe wheel. It is therefore desirableto avoid the presentation of anexcessive area-of such metal, *while retaining'the other characteristicswhich are desirable in a'brake shoe shell.

Ithasbeen previouslyn'oted that the portions 3of-the blank fromwhich'the shell is pressed are tapered outwardly toward the side-edgesof-the blank. This naturally resultsin theproduction of a shellwhich hassides taperin downwardly toward their lower edges. he thickness ofthemetal of the side strips 6 is thus greatest-where their width is least,andis least where their width is greatest;

By proportioning the width of the strips 6 at any pointalong'theirvertical extent'with the thickness of the strips-at suchpoint, the

area of metal in contact with the tread of a wheel array he maintainedconstant-at 'all -'t1mes duringthe 'usefulhfe of the brake shoe. Incomputing su'ch proportion, re-

gardshou'ld of course be -given to the effect produced by nnposmg thenecessary arcuate form on'the shell during the;pressing' operbrake shoeshell. By comparing theefl'ec- 'tive areas 18 of the strips as shown inFigure i8'with the effective areas 19 of" the strips asshown inFigure10, it is found that the sum of the areaslS, and the sum of the "areas19 is approximately equal. "This is true at any stage of wear during theeffective life of'the brake shoe.

It will be readily understood that "the brake shoe shell illustrated anddescribed herein 'presents an unusual combination of the qualities foundmost desirable in an arhole of such nature.

What I claim is:

1. A brake shoe shell for use with a filling of frictional compositionformed with integral back end and side Walls, the side walls of theshell comprising a plurality of strips with intervening apertures, saidstrips being so proportioned that the total areas of metal presented bythe strips of one side is approximately equal at any point along thevertical extent of the shell as the brake shoe wears away in use.

2. A brake shoe shell for use with a filling of frictional compositionformed with integral back end and side walls, the back wall being ofrelatively great thickness, and the side walls comprising a plurality ofstrips tapering in thickness from the back downwardly to the edges ofthe sides and having their width tapering upwardly to the back of theshell with interveningapertures between strips.

3. A brake shoe shell for use with a filling of frictional compositionformed with integral back end and side walls, the back wall being ofrelatively great thickness, and the side walls comprising a plurality ofstrips tapering in thickness from the back downwardly to the edges ofthe sides and having their width tapering upwardly to the back of theshell with intervening apertures between strips, said strips being soproportioned that the total area of metal presented by one side isapproximately equal at any point along the vertical extent of the shellas the brake shoe wears away in use.

In witness whereof, I hereunto set my hand.

MURRELL R. DE FRANCE.

